1.  G is approximately  b

       a. 6.67 x 10^-11 N m/kg²           b. 6.67 x 10^-11 N m²/kg²       c. 6.67 x 10^-11 m²/kg²        

Note: Using dimensional analysis, m₁m₂/r² gives kg²/m²

We know that force is expressed in newtons, so N has to appear somewhere

a. N appears but the m/kg² times the kg²/m² above leave an m in the denominator that is wrong

c. m²/kg²  cancels with the kg²/m²  but N is missing

b. Has the right units

2.  G was first measured by  b

      a. Newton       b. Cavendish      c. Galileo                      

      Details of the experiment: http://en.wikipedia.org/wiki/Cavendish_experiment

3. r is the distance  b

      a. from the surface of one body to the next   b.  between the centers of the 2 bodies    

4.  G in the above equation  b

      a.  is the same as g we have been using     b. is a universal constant     c. varies on different planets  

A body moving in uniform circular motion

Note: Uniform as used here means that the velocity is constant

1. Has an acceleration that is given by  b

     a.  a = v/r       b. a = v²/r     c. a = v/r²         

2. Has an acceleration vector that  b

    a. is parallel to v    b. points towards the circle’s center   c. points away from the center of the circle   

3. Has a frequency  a

    a. = 1/T where T is the period    b. = pr² , r is radius of the circle     c.  = 2p r , r is circle’s radius    

4. Has a velocity vector that  a

    a. is tangent to the circle   b. points outward from the circle’s center         

5. Has a net force that  a

    a. is centripetal           b. is tangent to the circle